Along with the development of mobile communication technologies, a user may access a wide area network (wide area network, WAN) in various manners, for example, a WAN port on a mobile wireless interconnection (wireless fidelity, wifi) device may include an Ethernet (Ethernet) port, a wifi station (station, STA) port, and a 2 G/3G/4G (second-generation/third-generation/fourth-generation mobile communication technologies) port, and the user may access the WAN in any one of the three manners. However, when the user uses the 2G/3G/4G port to transmit data, a large burden is caused to an operator network. Different from the operator network, a local area network (Local Area Network, LAN) usually uses a wifi network to access a wired network, for example, to access an optical fiber network, but the signal quality of the wifi network is usually unstable. On the premise of a stable data service, decision on using the 2G/3G/4G network or the wifi network to perform data transmission is a problem.